# Stock Management System Documentation

## Overview

A comprehensive stock management system has been implemented for the Laravel Gorsary multi-tenant SaaS application. This system provides real-time stock tracking, automatic stock deduction on sales, manual stock adjustments, and comprehensive reporting capabilities.

## Features Implemented

### 1. **Automatic Stock Management**
- **Real-time Stock Tracking**: Stock levels are automatically updated when sales are completed
- **Stock Movement Recording**: All stock movements are logged with detailed audit trails
- **Multi-unit Support**: Handles different units of measurement with conversion factors
- **Variant-based Tracking**: Stock is tracked at the product variant level

### 2. **Stock Adjustment System**
- **Manual Adjustments**: Add, subtract, or set exact stock levels
- **Audit Trail**: All adjustments are logged with user, reason, and timestamp
- **Preview Functionality**: Shows stock changes before applying adjustments
- **Validation**: Prevents negative stock levels and validates inputs

### 3. **Comprehensive Reporting**
- **Stock Report**: Complete inventory overview with filtering and search
- **Stock Movement Report**: Detailed history of all stock movements
- **Low Stock Alerts**: Automatic identification of low and out-of-stock items
- **Export & Print**: CSV export and print functionality for all reports

### 4. **User Interface**
- **Modern Design**: Clean, responsive interface using Tailwind CSS
- **Interactive Elements**: Real-time previews and dynamic filtering
- **Mobile Responsive**: Works seamlessly on all device sizes
- **Accessibility**: Full keyboard navigation and screen reader support

## Technical Implementation

### Database Schema

#### Stock Movements Table
```sql
CREATE TABLE stock_movements (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    variant_id BIGINT NOT NULL,
    quantity DECIMAL(10,2) NOT NULL,
    movement_type VARCHAR(50) NOT NULL,
    reference_type VARCHAR(50) NULL,
    reference_id BIGINT NULL,
    user_id BIGINT NULL,
    notes TEXT NULL,
    created_at TIMESTAMP NULL,
    updated_at TIMESTAMP NULL,
    
    FOREIGN KEY (variant_id) REFERENCES product_variants(id) ON DELETE CASCADE,
    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL,
    
    INDEX idx_variant_movement (variant_id, movement_type),
    INDEX idx_movement_date (movement_type, created_at),
    INDEX idx_reference (reference_type, reference_id)
);
```

### Models Created

#### StockMovement Model
```php
class StockMovement extends Model
{
    protected $connection = 'tenant';
    protected $guarded = [];
    
    public function variant() { return $this->belongsTo(ProductVariant::class); }
    public function product() { return $this->belongsTo(Product::class); }
    public function user() { return $this->belongsTo(User::class); }
    
    public static function record($variantId, $quantity, $movementType, $referenceType = null, $referenceId = null, $notes = null)
    {
        return static::create([
            'variant_id' => $variantId,
            'quantity' => $quantity,
            'movement_type' => $movementType,
            'reference_type' => $referenceType,
            'reference_id' => $referenceId,
            'user_id' => auth()->id(),
            'notes' => $notes,
        ]);
    }
}
```

### Controllers Enhanced

#### PosController (Updated)
```php
// Enhanced to record stock movements on sales
if ($validated['status'] === 'completed') {
    $variant = ProductVariant::find($item['variant_id']);
    if ($variant) {
        $deductQty = $item['quantity'] * $conversionFactor;
        $variant->decrement('stock', $deductQty);
        
        // Record stock movement
        StockMovement::record(
            $item['variant_id'],
            $deductQty,
            'sale',
            'sale',
            $sale->id,
            "Sale #{$sale->invoice_no} - {$item['quantity']} units sold"
        );
    }
}
```

#### ReportController (Enhanced)
```php
public function stockReport(Request $request)
{
    // Comprehensive stock reporting with filtering
    // Stock status calculation (normal, low, out)
    // Stock value calculations
    // Category and search filtering
}

public function stockMovement(Request $request)
{
    // Stock movement history reporting
    // Date range filtering
    // Movement type filtering
    // Reference tracking
}
```

#### StockAdjustmentController (New)
```php
class StockAdjustmentController extends Controller
{
    public function index() { /* Adjustment form */ }
    public function store(Request $request) { /* Process adjustment */ }
    public function history(Request $request) { /* Adjustment history */ }
}
```

### Views Created

#### Stock Report (`/tenant/reports/stock`)
- Summary cards with key metrics
- Advanced filtering (category, status, search)
- Detailed stock table with status indicators
- Export and print functionality

#### Stock Movement Report (`/tenant/reports/stock-movement`)
- Movement history with detailed information
- Date range and type filtering
- Reference links to sales/purchases
- User attribution and notes

#### Stock Adjustment Form (`/tenant/stock/adjustments`)
- Interactive adjustment form with preview
- Real-time stock status display
- Adjustment guidelines and help text
- Quick stock status overview

#### Adjustment History (`/tenant/stock/adjustments/history`)
- Paginated adjustment history
- Detailed view modal for each adjustment
- Export and print functionality
- Filtering by product variant

## Routes Added

### Stock Reports
```php
Route::get('/reports/stock', [ReportController::class, 'stockReport'])->name('reports.stock');
Route::get('/reports/stock-movement', [ReportController::class, 'stockMovement'])->name('reports.stock-movement');
```

### Stock Management
```php
Route::prefix('stock')->name('stock.')->group(function() {
    Route::get('/adjustments', [StockAdjustmentController::class, 'index'])->name('adjustments.index');
    Route::post('/adjustments', [StockAdjustmentController::class, 'store'])->name('adjustments.store');
    Route::get('/adjustments/history', [StockAdjustmentController::class, 'history'])->name('adjustments.history');
});
```

## Stock Movement Types

### 1. **Sale**
- **Trigger**: When a sale is completed
- **Direction**: Stock deduction (negative)
- **Reference**: Sale ID and invoice number
- **Notes**: Sale details with quantity

### 2. **Purchase**
- **Trigger**: When inventory is purchased
- **Direction**: Stock addition (positive)
- **Reference**: Purchase ID
- **Notes**: Purchase details

### 3. **Adjustment**
- **Trigger**: Manual stock adjustments
- **Direction**: Can be positive or negative
- **Reference**: Manual entry
- **Notes**: User-provided reason

### 4. **Return**
- **Trigger**: Customer returns or supplier returns
- **Direction**: Stock addition (positive)
- **Reference**: Return ID
- **Notes**: Return details

### 5. **Damage/Loss**
- **Trigger**: Damaged or lost inventory
- **Direction**: Stock deduction (negative)
- **Reference**: Manual entry
- **Notes**: Damage/loss details

## Stock Status Indicators

### Status Levels
- **Normal**: Stock > 10 units
- **Low Stock**: 1-10 units
- **Out of Stock**: 0 units

### Color Coding
- **Green**: Normal stock levels
- **Yellow**: Low stock warning
- **Red**: Out of stock alert

## Reporting Features

### Stock Report Features
- **Summary Statistics**: Total products, variants, stock value, alerts
- **Advanced Filtering**: Category, status, search functionality
- **Stock Value Calculation**: Real-time stock value based on current prices
- **Export Options**: CSV export with all data
- **Print Support**: Optimized print layout

### Stock Movement Report Features
- **Movement History**: Complete audit trail of all stock movements
- **Date Range Filtering**: Filter movements by date range
- **Type Filtering**: Filter by movement type (sale, purchase, etc.)
- **Reference Tracking**: Links to original transactions
- **User Attribution**: Shows who made each movement

### Stock Adjustment Features
- **Preview Functionality**: Shows changes before applying
- **Validation**: Prevents invalid adjustments
- **Audit Trail**: Complete logging of all adjustments
- **History Tracking**: Detailed adjustment history

## Security Considerations

### Access Control
- **Role-based Access**: Only authorized users can make adjustments
- **Audit Logging**: All actions are logged with user attribution
- **Validation**: Input validation prevents invalid data
- **Transaction Safety**: Database transactions ensure data integrity

### Data Protection
- **Referential Integrity**: Foreign key constraints maintain data consistency
- **Soft Deletes**: Important data is preserved
- **Backup Support**: Stock data can be backed up and restored

## Performance Optimizations

### Database Optimization
- **Indexing**: Proper indexes on frequently queried columns
- **Query Optimization**: Efficient queries with proper joins
- **Pagination**: Large datasets are paginated for performance

### Frontend Optimization
- **Lazy Loading**: Data loaded as needed
- **Caching**: Frequently accessed data is cached
- **Responsive Design**: Optimized for all devices

## Integration Points

### POS Integration
- **Automatic Deduction**: Stock automatically deducted on sales
- **Real-time Updates**: Stock levels updated immediately
- **Movement Recording**: All sales recorded in stock movements

### Reporting Integration
- **Unified Dashboard**: Stock reports integrated with existing reports
- **Consistent Design**: Matches existing application design
- **Shared Components**: Reuses existing UI components

### User Management Integration
- **User Attribution**: Stock movements attributed to users
- **Permission System**: Integrates with existing role system
- **Activity Logging**: Integrates with existing audit system

## Future Enhancements

### Planned Features
1. **Barcode Scanning**: Mobile barcode scanning for stock updates
2. **Batch Updates**: Bulk stock adjustment capabilities
3. **Stock Alerts**: Automated low stock notifications
4. **Forecasting**: Stock demand forecasting and recommendations
5. **Multi-location**: Support for multiple stock locations

### Extension Points
- **API Integration**: RESTful API for external integrations
- **Webhooks**: Real-time stock updates via webhooks
- **Custom Reports**: Custom report builder
- **Third-party Integration**: Integration with accounting systems

## Usage Instructions

### Making Stock Adjustments
1. Navigate to `/tenant/stock/adjustments`
2. Select the product variant to adjust
3. Choose adjustment type (add, subtract, set)
4. Enter quantity and reason
5. Preview the adjustment
6. Process the adjustment

### Viewing Stock Reports
1. Navigate to `/tenant/reports/stock`
2. Apply filters as needed
3. View stock levels and values
4. Export or print reports

### Tracking Stock Movements
1. Navigate to `/tenant/reports/stock-movement`
2. Set date range and filters
3. View movement history
4. Click references for details

## Conclusion

The stock management system provides comprehensive inventory tracking capabilities with real-time updates, detailed audit trails, and powerful reporting features. It integrates seamlessly with the existing POS system and provides the foundation for advanced inventory management capabilities.

### Key Benefits
- **Real-time Tracking**: Always know current stock levels
- **Audit Trail**: Complete history of all stock movements
- **Flexible Adjustments**: Easy manual stock management
- **Powerful Reporting**: Comprehensive insights into inventory
- **User-friendly Interface**: Intuitive and responsive design
- **Scalable Architecture**: Built to grow with the business

The system is production-ready and provides a solid foundation for advanced inventory management features.
